SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b892d70df1f62d387f8b9fa1f18289416b3a0d27962c06a20adcc097b5c1efe' 
  AND token = 'P+XYzBxfUDJuxhO+jUxMMfS5t43AtnWScbBHQiBqvSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}